U.S. patent application number 11/805777 was filed with the patent office on 2008-11-27 for moisture curable hot melt adhesive composition.
Invention is credited to Kevin J. Reid.
Application Number | 20080292902 11/805777 |
Document ID | / |
Family ID | 39683553 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080292902 |
Kind Code |
A1 |
Reid; Kevin J. |
November 27, 2008 |
Moisture curable hot melt adhesive composition
Abstract
A moisture curable hot melt adhesive composition includes a
polyurethane prepolymer, optionally a tackifying resin, and
optionally a thermoplastic polymer. The polyurethane prepolymer
includes a reaction product of an amorphous polyester polyol, a
polyisocyanate, and a crystalline monofunctional alcohol that has a
melting point of no less than about 80.degree. C.
Inventors: |
Reid; Kevin J.; (White Bear
Lake, MN) |
Correspondence
Address: |
H.B. Fuller;Patent Department
1200 Willow Lake Blvd., P.O. Box 64683
St. Paul
MN
55164-0683
US
|
Family ID: |
39683553 |
Appl. No.: |
11/805777 |
Filed: |
May 24, 2007 |
Current U.S.
Class: |
428/626 ;
156/332; 428/422.8; 525/101; 525/173; 525/451 |
Current CPC
Class: |
Y10T 428/31587 20150401;
C09J 2475/00 20130101; Y10S 526/935 20130101; C08G 18/2825
20130101; Y10T 428/31551 20150401; Y10T 428/3158 20150401; C08G
18/12 20130101; C08G 18/12 20130101; C08G 2170/20 20130101; C08G
18/307 20130101; Y10T 428/12569 20150115; Y10T 428/31547 20150401;
C08G 18/4233 20130101 |
Class at
Publication: |
428/626 ;
156/332; 428/422.8; 525/101; 525/173; 525/451 |
International
Class: |
B32B 15/095 20060101
B32B015/095; B32B 21/08 20060101 B32B021/08; B32B 27/08 20060101
B32B027/08; C08G 18/61 20060101 C08G018/61; C08G 18/72 20060101
C08G018/72 |
Claims
1. A moisture curable hot melt adhesive composition comprising: a
polyurethane prepolymer that comprises a reaction product of an
amorphous polyester polyol that is a reaction product of a polyol
and a dimerized fatty acid, a polyisocyanate, and a crystalline
monofunctional alcohol having a melting point of no less than about
80.degree. C.; optionally a tackifying resin; and optionally a
thermoplastic polymer.
2. The adhesive composition of claim 1, wherein said monofunctional
alcohol has carbon atoms of no less than 35.
3. The adhesive composition of claim 1, comprising from about 10%
by weight to about 80% by weight said polyurethane prepolymer, from
about 1% by weight to about 70% by weight said tackifying resin,
and from about 10% by weight to about 70% by weight said
thermoplastic polymer.
4. The adhesive composition of claim 1, wherein said polyurethane
prepolymer exhibits a glass transition temperature of no greater
than about 10.degree. C.
5. The adhesive composition of claim 1, wherein said composition
exhibits a melt viscosity of no greater than about 150,000 cps at
250.degree. F. (121.degree. C.).
6. The adhesive composition of claim 1, wherein said thermoplastic
polymer is selected from the group consisting of polyolefin's,
polyalphaolefins, polyesters having number average molecular weight
of greater than about 10,000 g/mole, ethylene vinyl acetate,
polyacrylates, polymethacrylates, polyacrylamides,
polyacrylonitriles, polyimides, polyamides, polyvinyl chloride,
polysiloxanes, polyurethanes, polystyrene, polyetheramide
copolymers, styrene-butadiene copolymers, styrene-butadiene-styrene
copolymers, styrene-isoprene-styrene copolymers,
styrene-ethylene-butylene-styrene copolymers,
styrene-ethylene-propylene-styrene copolymers, butyl rubber,
polyisobutylene, isobutylene-isoprene copolymers, hydroxyl
functional versions of any of the aforesaid polymers, and
combinations thereof.
7. The adhesive composition of claim 1, wherein said dimerized
fatty acid comprises a reaction product of two unsaturated carboxyl
acids, each having carbon atoms of no less than 12.
8. A moisture curable hot melt adhesive composition comprising a
polyurethane prepolymer that comprises a reaction product of an
amorphous polyester polyol, a polyisocyanate, and a crystalline
monofunctional alcohol having a melting point of no less than about
80.degree. C.; optionally a tackifying resin; and optionally a
thermoplastic polymer, wherein said composition is free of a
crystalline or a semi crystalline polyester polyol.
9. The adhesive composition of claim 8, comprising from about 10%
by weight to about 80% by weight said polyurethane prepolymer, from
about 1% by weight to about 70% by weight said tackifying resin,
and from about 10% by weight to about 70% by weight said
thermoplastic polymer.
10. The adhesive composition of claim 8, wherein said composition
exhibits a melt viscosity of from about 5,000 cps to about 150,000
cps at 250.degree. F. (121.degree. C.).
11. The adhesive composition of claim 8, wherein said prepolymer
has a weight average molecular weight of at least about 20,000
g/mol.
12. The adhesive composition of claim 8, wherein said thermoplastic
polymer is selected from the group consisting of polyolefins,
polyalphaolefins, polyesters, ethylene vinyl acetate,
polyacrylates, polymethacrylates, polyacrylamides,
polyacrylonitriles, polyimides, polyamides, polyvinyl chloride,
polysiloxanes, polyurethanes, polystyrene, polyetheramide
copolymers, styrene-butadiene copolymers, styrene-butadiene-styrene
copolymers, styrene-isoprene-styrene copolymers,
styrene-ethylene-butylene-styrene copolymers,
styrene-ethylene-propylene-styrene copolymers, butyl rubber,
polyisobutylene, isobutylene-isoprene copolymers, hydroxyl
functional versions of any of the aforesaid polymers, and
combinations thereof.
13. The adhesive composition of claim 8, wherein said amorphous
polyester polyol comprises a reaction product of a polyol and a
dimerized acid.
14. A process of bonding a first substrate to a second substrate,
comprising: applying the moisture curable hot melt adhesive
composition of claim 1 on at least one surface of a first
substrate, contacting said adhesive composition with a second
substrate, and curing said adhesive composition.
15. A process of bonding a first substrate to a second substrate,
comprising: applying the moisture curable hot melt adhesive
composition of claim 8 on at least one surface of a first
substrate, contacting said adhesive composition with a second
substrate, and curing said adhesive composition.
16. An article comprising a first substrate, a second substrate and
the adhesive composition of claim 1 sandwiched between said first
and second substrates.
17. The article of claim 16, wherein at least one of said first and
second substrates is selected from the group consisting of
acrylonitrile-butadiene-styrene (ABS), fiber reinforced plastic
(FRP), wood, wood composite panels, polyvinyl chloride (PVC),
paper, impact modified polystyrene, polycarbonate, foamed
polystyrene, metals, painted metals, galvanized metals, and
combinations thereof.
18. An article comprising a first substrate, a second substrate and
the adhesive composition of claim 8 sandwiched between said first
and second substrates.
19. The article of claim 18, wherein at least one of said first and
second substrates is selected from the group consisting of
acrylonitrile-butadiene-styrene (ABS), fiber reinforced plastic
(FRP), wood, wood composite panels, polyvinyl chloride (PVC),
paper, impact modified polystyrene, polycarbonate, foamed
polystyrene, metals, painted metals, galvanized metals, and
combinations thereof.
Description
[0001] The invention relates to a moisture curable hot melt
adhesive composition including a moisture curable polyurethane
prepolymer. In particular, the moisture curable polyurethane
prepolymer includes a reaction product of an amorphous polyester
polyol, a polyisocyanate, and a crystalline monofunctional
alcohol.
BACKGROUND OF THE INVENTION
[0002] Both hot melt adhesives and moisture curable hot melt
polyurethane adhesives are well known generic adhesive classes. A
hot melt adhesive can be conveniently applied by extruding the
adhesive at an elevated temperature directly onto a work piece to
form a structural bond with another work piece as the temperature
of the adhesive cools. While hot melt adhesives have many adhesive
preparation and work piece production benefits, they have an
effective temperature use range that is lower than their
application temperature. In other words, the adhesives can lose
bond strength as the temperature of the work piece and the bond
line increase.
[0003] In sharp contrast, moisture curable hot melt polyurethane
adhesives have little green strength in their open state, limited
peel and shear strength after set and require curing before these
properties improve. After application of an adhesive, the joined
work pieces may require external mechanical support until the
adhesive cures to a strong resilient, crosslinked bond line. A
cured polyurethane adhesive bond has high tensile strength, which
can be maintained above its application temperature e.g., from
about 100.degree. C. to about 130.degree. C. Such adhesives have
value where initial green strength is not important since
substantial bond formation requires a period of curing time, which
can range from hours to a number of days.
[0004] Clearly a moisture curable hot melt adhesive that displays
the high initial peel and shear strength of a hot melt and that
builds in bond strength over time is desirable. Early attempts to
formulate such an adhesive have been made but none have been
entirely successful. Some early formulas set as a hot melt
adhesive, but produced only modest increases in heat resistance
when fully cured. Other early adhesives may have good green
strength, but short open times, low heat resistance as cured,
(e.g., low peel adhesion failure temperature (PAFT)), and limited
adhesion to plastics. Accordingly, a substantial need exists in
finding better moisture curable hot melt adhesive formulations.
SUMMARY OF THE INVENTION
[0005] In one aspect, the invention features a moisture curable hot
melt adhesive composition that includes a moisture curable
polyurethane prepolymer. The polyurethane prepolymer includes a
reaction product of an amorphous polyester polyol, a
polyisocyanate, and a crystalline monofunctional alcohol.
[0006] In one embodiment the adhesive composition further includes
a tackifying resin.
[0007] In other embodiments, the adhesive composition further
includes a thermoplastic polymer.
[0008] In one embodiment, the adhesive composition is free of a
crystalline or a semi crystalline polyester polyol. That is, the
composition does not include a crystalline or a semi crystalline
polyester polyol as a reactant. In other words, the composition
does not include a reaction product that includes a crystalline or
a semi crystalline polyester polyol as a reactant.
[0009] In one embodiment, the amorphous polyester polyol includes a
reaction product of a polyol and a dimerized fatty acid.
[0010] In one embodiment, the amorphous polyester polyol has a
hydroxyl number of from about 30 to about 210, or from about 30 to
about 80.
[0011] In another embodiment, the amorphous polyester polyol has a
glass transition temperature of from about 0.degree. C. to about
-50.degree. C., or from about -20.degree. C. to about -50.degree.
C.
[0012] In some embodiments, the crystalline monofunctional alcohol
has a melting point of from about 80.degree. C. to about
100.degree. C.
[0013] In one embodiment, the crystalline monofunctional alcohol
has a weight average molecular weight of from about 400 g/mol to
about 1,000 g/mol, in some embodiments from about 450 g/mol to
about 500 g/mol.
[0014] In one embodiment, the polyurethane prepolymer has a weight
average molecular weight of at least about 20,000 g/mole.
[0015] In one embodiment, the adhesive composition exhibits a melt
viscosity of from about 5,000 centipoises (cps) to about 150,000
cps, in other embodiments from about 5,000 cps to about 50,000 cps
at 250.degree. F. (121.degree. C.).
[0016] The adhesive composition exhibits very good adhesion to wood
and plastic substrates. The adhesive composition also exhibits fast
setting, high green strength, good flexibility at low temperatures,
and high heat resistance at elevated temperatures.
[0017] The adhesive composition can be applied by roll coating,
extruding, or spraying.
[0018] In another aspect, the invention features an article that
includes a first substrate, a second substrate, and any one of the
aforesaid moisture curable hot melt adhesive compositions
sandwiched between the first and the second substrates.
[0019] In other aspects the invention features a moisture curable
polyurethane prepolymer that includes a reaction product of an
amorphous polyester polyol, polyisocyanate, and a crystalline
monofunctional alcohol. In one embodiment, the monofunctional
alcohol has from 20 to 100 carbon atoms. In one embodiment, the
polyester polyol includes a reaction product of a polyol and a
dimerized acid. In other embodiments, the crystalline
monofunctional alcohol has a melting point of from about 80.degree.
C. to about 100.degree. C.
[0020] In another aspect, the invention features an article that
includes a first substrate, a second substrate, and any one of the
aforesaid moisture curable polyurethane prepolymers sandwiched
between the first and the second substrates.
[0021] In still other aspects, the invention features a method of
bonding a first substrate to a second substrate. The method
includes contacting a first substrate with any one of the aforesaid
moisture curable polyurethane prepolymers, or any one of the
aforesaid moisture curable hot melt adhesive compositions, and
contacting the prepolymer or the adhesive composition with a second
substrate.
[0022] In one embodiment, at least one of the first and the second
substrates includes a material chosen from
acrylonitrile-butadiene-styrene (ABS), fiber reinforced plastic
(FRP), wood, wood composite panels, polyvinyl chloride (PVC),
paper, impact modified polystyrene, polycarbonate, foamed
polystyrene, metals, painted metals, or galvanized metals, or
combinations thereof.
[0023] Other features and advantages will be apparent from the
following description of the preferred embodiments and from the
claims.
DETAILED DESCRIPTION
[0024] The moisture curable hot melt adhesive composition includes
a moisture curable polyurethane prepolymer, and optionally a
tackifying resin, and optionally a thermoplastic polymer.
Polyurethane Prepolymer
[0025] The moisture curable polyurethane prepolymer is referred to
hereinafter as "polyurethane prepolymer" or "prepolymer".
[0026] The polyurethane prepolymer has a melt viscosity of from
about 500 cps to about 70,000 cps, or from about 2,000 cps to about
40,000 cps, or from about 5,000 cps to about 25,000 cps at
250.degree. F. (121.degree. C.). The polyurethane prepolymer has a
glass transition temperature of no greater than about 10.degree.
C.
[0027] The polyurethane prepolymer is prepared by reacting
polyisocyanate, an amorphous polyester polyol, and a crystalline
monofunctional alcohol to form the isocyanate terminated prepolymer
that has at least two isocyanate functional groups capable of
reacting with moisture or other reactive hydrogen containing
compounds.
[0028] Useful methods of preparing isocyanate functional
polyurethane prepolymers are disclosed in a number of references
including, e.g., U.S. Pat. Nos. 6,355,317, 6,387,449, 5,965,662,
4,808,255, and 4,775,719, which are incorporated herein by
reference.
[0029] Preferably the polyester polyol and the monofunctional
alcohol are reacted with excess diisocyanate (i.e., the amount of
isocyanate functional groups present in the reaction mixture is
greater than the number of hydroxy equivalents present in the
reaction mixture) in a first step to form the isocyanate functional
polyurethane prepolymer. Preferably the ratio of isocyanate groups
(NCO) to hydroxy groups (OH) in the reaction mixture is sufficient
to obtain an isocyanate concentration in the final composition of
from about 1% by weight to about 10% by weight as measured by ASTM
D-2572-80. Preferably the ratio of the isocyanate groups to the
hydroxy groups in the reaction mixture is from about 1.1:1 to about
4:1, or from about 2:1 to about 3:1. Preferred polyurethane
prepolymers have an average functionality (i.e., average number of
isocyanate functional groups) of at least about 1.8, or at least
about 2, or no greater than about 3.
[0030] The polyurethane prepolymer is present in the adhesive
composition in an amount of up to about 100% by weight, or from
about 10% by weight to about 80% by weight, or from about 20% by
weight to about 70% by weight, or from about 20% by weight to about
50% by weight, based on the total weight of the composition.
Polyisocyanate
[0031] The polyisocyanate can be any suitable isocyanate compounds
that have at least two isocyanate groups including, e.g.,
aliphatic, cycloaliphatic, araliphatic, arylalkyl, alkylaryl, and
aromatic isocyanates, and mixtures thereof. The isocyanate
compounds can also contain other substituents that do not
substantially adversely affect the viscosity of the prepolymer, the
adhesive properties of the bond line, or the reactivity of the
isocyanate groups during the formation of the prepolymer. The
isocyanate compound can also include mixtures of aromatic and
aliphatic isocyanates, as well as isocyanate compounds having both
aliphatic and aromatic character.
[0032] Typical aromatic isocyanate compounds include
diphenylmethane diisocyanate compounds (MDI) including its isomers,
carbodiimide modified MDI, diphenylmethane-4,4'-diisocyanate,
diphenylmethane-2,2'-diisocyanate,
diphenyl-methane-2,4'-diisocyanate, oligomeric phenyl methylene
isocyanates; toluene diisocyanate compounds (TDI) including isomers
thereof, tetramethylxylene diisocyanate (TMXDI), isomers of
naphthylene diisocyanate, isomers of triphenylmethane
triisocyanate, and mixtures thereof. Aliphatic di, tri, and
polyisocyanates are also useful including for example isophorone
diisocyanate, hydrogenated aromatic diisocyanates, aliphatic
polyisocyanates, cycloaliphatic polyisocyanates, and others. Other
useful isocyanates are disclosed in, e.g., U.S. Pat. Nos.
6,803,412; 6,387,449; 6,355,317; 6,221,978; 4,820,368; 4,808,255;
4,775,719; and 4,352,85, which are incorporated herein by
reference.
[0033] Particularly preferred diisocyanates are blends of
2,4'-methylene diphenyl diisocyanate and 4,4-methylene diphenyl
diisocyanate.
[0034] Useful commercially available aromatic isocyanates include,
e.g., aromatic isocyanates available under the trade designations
MONDUR ML from Bayer (Pittsburgh, Pa.), ISONATE 50 OP and ISONATE
125M from Dow Chemical Company (Midland, Mich.), and LUPRANATE MI
from BASF (Germany).
Polyester Polyol
[0035] Suitable polyester polyols useful in the preparation of the
prepolymer are amorphous polyester polyols. Contrary to crystalline
or semi crystalline polyester polyols that have a crystalline
melting point, amorphous polyester polyols do not have
crystallinity, therefore, do not have a crystalline melting
point.
[0036] Preferably, useful amorphous polyester polyols have a
functionality of from about 2 to about 3, or from about 2.1 to
about 2.4.
[0037] Examples of amorphous polyester polyols include those that
are reaction products of polyol/diol and ricinoleic acid, e.g.,
Polycin.RTM. GR-Polyols from Vertellus Performance Material INC.
(Greensboro, N.C.).
[0038] Preferably, the amorphous polyester polyols are dimer acid
based polyester polyols. By "dimer acid based polyester polyol" it
refers to a reaction product of a monomeric polyol and a dimerized
fatty acid. A dimerized fatty acid is an oligomerisation product of
two unsaturated fatty acids and has two or more carboxylic
functionalities. Preferably, the unsaturated fatty acids have at
least 12 carbon atoms, or up to 24 carbon atoms. In one embodiment,
the unsaturated fatty acid has 18 carbon atoms. Examples of
commercially available dimerized fatty acid include PRIPOL 1017,
1013 and 1006 from Uniqema (Chicago, Ill.).
[0039] Examples of suitable monomeric polyols from which dimer acid
based polyester polyols can be derived include ethylene glycols,
propane diols (e.g., 1,2-propanediol and 1,3-propanediol), butane
diols (e.g., 1,3-butanediol), 1,5-pentanediol, 1,6-hexanediol,
1,8-octanediol, 1,10-decanediol, neopentyl glycol, diethylene
glycol, triethylene glycol, tetraethylene glycol, polyethylene
glycols, polypropylene glycols (e.g., dipropylene glycol and
tripropylene glycol)1,4-cyclohexanedimethanol, 1,4-cyclohexanediol,
dimer diols, bisphenol A, bisphenol F, hydrogenated bisphenol A,
hydrogenated bisphenol F, glycerol, and combinations thereof.
[0040] Examples of useful commercially available dimer acid-based
polyester polyols include those under PRIPLAST series of trade
designations including, e.g., PRIPLAST 3187, 3190, 3196, and 3197
from UNIQEMA (New Castle, Del.)
[0041] The amorphous polyester polyols useful in the preparation of
the polyurethane prepolymers of the invention are tailored in
polarity to the polarity of the thermoplastic polymer, for example,
ethylene vinyl acetate (EVA) copolymer used in the adhesive. The
polarity of a polyester polyol can be estimated using the average
equivalent weight of the monomeric polyol and the average
equivalent weight of the polyacid. For ethylene vinyl acetate
copolymers having 50% vinyl acetate or more, the sum of the average
equivalent weight of the polyol and the polyacid is from about 150
to about 500. For an ethylene vinyl acetate having a vinyl acetate
content of about 28% to 50%, the sum of the average equivalent
weight of the polyol and the polyacid is from about 150 to about
600 or preferably 200 to 500. For an ethylene vinyl acetate having
a vinyl acetate content of 28% or less the sum of the average
equivalent weight of the polyol and the polyacid is from about 250
to about 300, and preferably from about 300 to about 1500.
[0042] The molecular weight of the amorphous polyester polyol is
conversely proportional with the polarity of the resultant
polyurethane prepolymer. That is, the polarity of the prepolymer
increases as the molecular weight of the amorphous polyester polyol
decreases. Therefore, one could adjust the molecular weight of the
amorphous polyester polyol to obtain the prepolymer with a
desirable polarity, which matches with the polarity of the
thermoplastic polymer, e.g., an EVA copolymer to enhance the
compatibility of the adhesive.
Monofunctional Alcohol
[0043] The monofunctional alcohol suitable for the preparation of
the polyurethane prepolymer of the invention is crystalline and
preferably an alkyl alcohol having from 20 to 100, or from 30 to
60, or from 40 to 50 carbon atoms.
[0044] Useful monofunctional alcohols have a melting point of from
about 70.degree. C. to about 100.degree. C., or from about
80.degree. C. to about 100.degree. C.
[0045] Examples of useful commercially available monofunctional
alcohols include UNILIN series of trade designation, e.g., UNILIN
350, 425, 550 and 700 from Baker Petrolite (Sugar Land, Tex.).
[0046] Monofunctional alcohol is preferably present in the reaction
mixture in an amount of from about 5% to about 40%, or from about
10% to about 25% of polyol equivalents in the prepolymer.
Thermoplastic Polymer
[0047] The adhesive composition of the invention may include a
thermoplastic polymer. Suitable thermoplastic polymers are
compatible and cooperate with the other adhesive components to
provide the initial green strength and the final cured strength.
Preferably, the thermoplastic polymer is matched in polarity with
the polyurethane prepolymer and with the tackifier.
[0048] The preferred thermoplastic polymer component includes
ethylene vinyl monomer polymers such as an ethylene vinyl acetate
(EVA) copolymers, or polymers containing carboxylic acid
groups.
[0049] In one embodiment, the preferred polyurethane prepolymers
are formulated to have a polarity compatible with ethylene vinyl
acetate (EVA) copolymers having from about 10% to about 60% vinyl
acetate and a melt index of from about 0.2 g/min to about 1000
g/min. The most preferred EVA copolymers includes those that have
from about 18% to 50% vinyl acetate and a melt index of about 0.2
g/min to 500 g/min.
[0050] Examples of other useful thermoplastic polymers include
polyurethanes, polystyrene, polyetheramide block copolymers,
polyesters, butadiene-styrene elastomers including, e.g., A-B,
A-B-A, A-(B-A)n-B, (A-B)n-Y, and radial block copolymers and
grafted versions thereof where the A block(s) is a polyvinyl
aromatic block (e.g., styrene), and the B block is a rubbery
midblock (e.g., isoprene, butadiene, ethylene-butylene, and
ethylene-propylene) (e.g., styrene-butadiene-styrene block
copolymers, styrene-isoprene-styrene block copolymers,
styrene-ethylene-butylene-styrene block copolymers,
styrene-ethylene-propylene-styrene block copolymers), polyurethane
elastomers, polyolefin elastomers, hydroxyl functional versions of
any of the aforesaid polymers, and combinations thereof.
[0051] Useful commercially available thermoplastic polymers include
e.g., ethylene vinyl acetate copolymers available under the ELVAX
series of trade designations from DuPont de Nemours (Wilmington,
Del.) and the ULTRATHENE series of trade designations from
Millennium Petrochemicals (Rolling Meadows, Ill.); ethylene methyl
acrylate copolymers available under the OPTEMA series of trade
designations from Exxon Chemical Co. (Houston, Tex.); ethylene
n-butyl acrylate copolymers available under the LOTRYL series of
trade designations from Elf Atochem North America (Philadelphia,
Pa.), the ESCORENE series of trade designations from Exxon Chemical
Co. and the ENATHENE series of trade designations from Millennium
Petrochemicals; ethylene n-butyl acrylate carbon monoxide
terpolymers available under the ELVALOY series of trade
designations from DuPont; thermoplastic polyurethane polymers
available under the PEARLSTICK series of trade designations from
Aries Technologies (Derry, N.H. a distributor for Merquinsa,
Barcelona, Spain); butylene/poly(alkylene ether) phthalate polymers
available under the HYTREL series of trade designations from
DuPont; ethylene acrylate copolymers also available under the
ELVALOY series of trade designations from DuPont; and acrylic
polymers available under the ELVACITE series of trade designations
from ICI Acrylics (St. Louis, Mich.); isobutylene-isoprene
copolymers available the BUTYL Rubber series of trade designations
including BUTYL 268 and BUTYL 065 from Exxon Chemical Co. (Houston,
Tex.); ethylene-propylene copolymers available under the VISTALON
series of trade designations including, e.g., VISTALON 404, from
Exxon Chemical Co.; styrene-ethylene/butylene-styrene block
copolymers available under the KRATON G series of trade
designations including, e.g., KRATON G-1652 and G-1657, from Shell
Chemical Co. (Houston, Tex.); styrene-butadiene-styrene and
styrene-isoprene-styrene block copolymers available under the
KRATON D series of trade designations including, e.g., KRATON
D-1111 and D-1112 from Shell Chemical Co.; silane terminated block
copolymers available under the KRATON SKFG101 trade designation
from Shell Chemical Co.; and styrene-butadiene-styrene and
styrene-isoprene-styrene block copolymers available under the
VECTOR series of trade designations including, e.g., VECTOR 4112,
4114 and 4411 from Dexco Polymers (Houston, Tex.).
[0052] The thermoplastic polymer is present in the composition in
an amount of up to about 70% by weight, or from about 10% by weight
to about 70% by weight, or from about 20% by weight to about 50% by
weight of a thermoplastic polymer, based on the total weight of the
composition.
Tackifying Resin
[0053] The adhesive composition may include a tackifying resin.
Preferred tackifying resins have a ring and ball softening point of
from about 70.degree. C. to about 150.degree. C., or from about
80.degree. C. to about 120.degree. C. Examples of suitable
tackifying agents include aliphatic, cycloaliphatic, aromatic,
aliphatic-aromatic, aromatic modified alicyclic, and alicyclic
hydrocarbon resins and modified versions and hydrogenated
derivatives thereof; terpenes (polyterpenes), modified terpenes
(e.g., phenolic modified terpene resins), and mixture thereof.
Other useful tackifying agents are disclosed in, e.g., U.S. Pat.
No. 6,355,317 incorporated herein by reference.
[0054] Suitable commercially available tackifying resins include,
e.g., partially hydrogenated cycloaliphatic petroleum hydrocarbon
resins available under the EASTOTAC series of trade designations
including, e.g., EASTOTAC H-100, H-115, H-130 and H-142 from
Eastman Chemical Co. (Kingsport, Tenn.) available in grades E, R, L
and W, which have differing levels of hydrogenation from least
hydrogenated (E) to most hydrogenated (W), the ESCOREZ series of
trade designations including, e.g., ESCOREZ 5300 and ESCOREZ 5400
from Exxon Chemical Co. (Houston, Tex.), and the HERCOLITE 2100
trade designation from Hercules (Wilmington, Del.); partially
hydrogenated aromatic modified petroleum hydrocarbon resins
available under the ESCOREZ 5600 trade designation from Exxon
Chemical Co.; aliphatic-aromatic petroleum hydrocarbon resins
available under the WINGTACK EXTRA trade designation from Goodyear
Chemical Co. (Akron, Ohio); styrenated terpene resins made from
d-limonene available under the ZONATAC 105 LITE trade designation
from Arizona Chemical Co. (Panama City, Fla.); aromatic
hydrogenated hydrocarbon resins available under the REGALREZ 1094
trade designation from Hercules; and alphamethyl styrene resins
available under the trade designations KRISTALEX 3070, 3085 and
3100, which have softening points of 70.degree. C., 85.degree. C.
and 100.degree. C., respectively, from Hercules.
[0055] The tackifying resin is present in an amount of up to about
70% by weight, or from about 1% by weight to about 70% by weight,
or from about 20% by weight to about 50% by weight, based on the
total weight of the composition.
[0056] The adhesive composition may also include other additives
including, e.g., fillers, ultraviolet light stabilizers,
antioxidants, catalysts, rheology modifiers, adhesion promoters
e.g., silanes and alkyl silanes, biocides, corrosion inhibitors,
dehydrators, organic solvents, colorants (e.g., pigments and dyes),
surfactants, flame retardants, waxes, and mixtures thereof.
Suitable fillers include, e.g., fumed silica, precipitated silica,
talc, calcium carbonates, carbon black, aluminasilicates, clay,
zeolites, ceramics, mica, titanium dioxide, and combinations
thereof.
[0057] The adhesive composition is particularly useful for bonding
wood to various substrates including wood, metal, plastic
substrates (e.g., PVC, ABC and polycarbonate), metallic substrates,
composites (e.g., polymer and wood fiber composites), and
combinations thereof.
[0058] The invention will now be described by way of the following
examples. All parts, ratios, percents, and amounts stated in the
examples are by weight unless otherwise specified.
EXAMPLES
Test Procedures
[0059] Test procedures used in the examples include the
following.
Peel Adhesion
[0060] A test sample is prepared as follows: a moisture curable hot
melt adhesive composition is melted at 120-130.degree. C., and
transferred to the rolls of a Union Tool roll coater. The rolls are
heated to 270-280.degree. F. (132-138.degree. C.); the temperature
of the adhesive on the rolls is 265-270.degree. F. The adhesive
composition is coated on a piece of 0.5-inch-thick wood
particleboard at 10-12 gram per square foot. Thereafter, the
adhesive coating is quickly mated with a clean ABS substrate and
pressed on a heated press at 160-180.degree. F. (71-82.degree. C.)
for 20 seconds. The bond is cured in a controlled environment room
at 75.degree. F. and 50% relative humidity (RH) for 7-10 days.
[0061] Prior to testing, samples are conditioned at 50% RH and a
testing temperature for 2-4 hours. Then, a sample is secured in a
vise and pulled by human hands in peel direction within seconds
upon removal from each conditioned environment. The adhesion on
wood particle board is observed and reported as percent wood
failure (% WF), percent cohesive failure (% CF) and percent
adhesive failure (% AF). The higher the percent wood failure is,
the stronger the adhesion is.
Examples
Preparation of Polyol 1
[0062] 290 grams (g) Empol TM 1018 (a dimerized acid from Cognis,
Cincinnati, Ohio) and 71 g neopentyl glycol are charged in a flask
equipped with a mechanical stirrer and a Dean-Stark trap for
collecting water from the condensation reaction. The reaction is
carried out at 100-140.degree. C. under 28-inch Hg vacuum for 4-6
hours until the acid number is below 0.80. The polyol produced has
a hydroxyl number of 55 and is designated as Polyol 1.
Preparation of Polyol 2:
[0063] 290 g Empol TM 1061 (a dimerized acid from Cognis) and 71 g
neopentyl glycol are charged in a flask equipped with a mechanical
stirrer and a Dean-Stark trap for the collection water fro the
condensation reaction. The reaction was carried out at
100-140.degree. C. under 28-inch Hg vacuum for 4-6 hours until the
acid number was below 0.80. The polyol produced has a hydroxyl
number of 55 and is designated as Polyol 2.
Comparative Example 1
[0064] A moisture curable hot melt polyurethane adhesive
composition is prepared according to Example 19 of U.S. Pat. No.
6,387,442. Peel adhesion of the composition is tested according to
the Peel Adhesive test method and the results are listed in Table
I.
Comparative Example 2
[0065] A moisture curable hot melt polyurethane adhesive
composition is prepared by mixing 155.4 g Polyol 2 with 198 g Elvax
150, 168 g Escorez 5615 and 30 g Sasolwax C80 (from Sasol Wax
Americas, Shelton, Conn.) at 220-260.degree. F. (104-126.degree.
C.) until smooth for 30-60 minutes. Then 48.6 g Rubinate 1225 (MDI
from Huntsman Chemical, Houston, Tex.) is added and reacted for
1-1.5 hours at 220-275.degree. F. (104-135.degree. C.). Thereafter,
1-2 drops of Jeffcat DMDEE is added and mixed for 10-15 minutes.
The viscosity of the composition is 37,000 cps at 250.degree. F.
(121.degree. C.). Peel adhesion of the composition is tested
according to the Peel Adhesive test method and the results are
listed in Table I.
Comparative Example 3
[0066] A moisture curable hot melt polyurethane adhesive
composition is prepared by mixing 155.4 g Polyol 2 with 198 g Elvax
150, and 198 g Escorez 5615 at 220-260.degree. F. (104-126.degree.
C.) until smooth for 30-60 minutes. Then 48.6 g Rubinate 1225 (MDI
from Huntsman Chemical) is added and reacted for 1-1.5 hours at
220-275.degree. F. (104-135.degree. C.). Thereafter, 1-2 drops of
Jeffcat DMDEE is added and mixed for 10-15 minutes. The viscosity
of the composition is 56,500 cps at 250.degree. F. (121.degree.
C.). Peel adhesion of the composition is tested according to the
Peel Adhesive test method and the results are listed in Table
I.
Example 1
[0067] A moisture curable hot melt polyurethane adhesive
composition is prepared by mixing 148.2 g Polyol 2 with 7.2 g
Unlink 550 (a monofunctional alcohol from Baker Petrolite, Sugar
Land, Tex.),. 198 g Elvax 150 and 198 g Escorez 5615 at
220-260.degree. F. (104-126.degree. C.) until smooth for 30-60
minutes. Then 49.6 g Rubinate 1225 (MDI from Huntsman Chemical) is
added and reacted for 1-1.5 hours at 220-275.degree. F.
(104-135.degree. C.). Thereafter, 393 1-2 drops of Jeffcat DMDEE is
added and mixed for 10-15 minutes. The viscosity of the composition
is 56,400 cps at 250.degree. F. (121.degree. C.). Peel adhesion of
the composition is tested according to the Peel Adhesive test
method and the results are listed in Table I.
TABLE-US-00001 TABLE I 24.degree. C. 80.degree. C. -23.degree. C.
Comp. Ex. 1 100% WF 80% WF/20% CF 100% AF Comp. Ex. 2 90% WF/10% AF
50% CF/50% AF 100% AF Comp. Ex. 3 100% WF 80% CF/20% AF 100% WF Ex.
1 100% WF 80% WF/20% CF 100% WF
[0068] While numerous embodiments and examples have been disclosed
herein, it should be apparent that modifications can be made
without departing from the spirit and scope of the invention.
Therefore, the appended claims are intended to cover all such
modifications that are within the scope of this invention. The
relevant portions of all documents disclosed herein are hereby
incorporated by reference in their entirety.
[0069] Other embodiments are within the claims.
* * * * *